Tribological properties of ta-CNx coating sliding against steel and sapphire in unlubricated condition

Xiaoxu Liu, Noritsugu Umehara, Takayuki Tokoroyama, Motoyuki Murashima

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


Tribo-behavior of tetrahedral amorphous carbon nitride (ta-CNx) coating in unlubricated condition was investigated in this study. Sliding against steel, low nitrogen content ta-CNx exhibits much lower friction and wear as temperature increases, with less adhesion wear than ta-C and remained relatively higher hardness (45.01 GPa). Nevertheless, against sapphire ta-C outperforms ta-CNx greatly, and graphitization could be found at 120 °C. With atmosphere humidity increasing, ta-CNx shows significantly decreased friction, implying the tribo-character of high sp3 bonding structure. Meanwhile, dry air seems to be the harshest condition for ta-CNx, since O2 in the atmosphere might lead to oxidized wear of ta-CNx even under room temperature. Furthermore, in humid N2, as an inert gas with high humidity, ta-CNx shows the lowest friction and wear.

Original languageEnglish
Pages (from-to)102-111
Number of pages10
JournalTribology International
Publication statusPublished - 2019 Mar
Externally publishedYes


  • Gas atmosphere
  • ta-CNx coating
  • Temperature
  • Tribological property

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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